The present invention relates to an apparatus useful in the detection of the presence or absence of a person in a bed. More particularly, the invention relates to detection devices incorporated in a hospital bed structure and external circuitry at bedside for relaying information to personnel at a central call board.
Unauthorized departures of patients from their beds are a serious problem in providing care to the sick and infirm. Prevention of these departures, and the falls which may result, require a high level of surveillance. If injury results, legal action may be taken against the health care personnel and the institution. The personnel or institution may be found liable, if reasonable precautions have not been taken to prevent the unauthorized departure or fall.
A number of different types of bed monitoring systems have been proposed. Most of such systems employ a movable detector which can be deployed in various positions under the bed mattress or under the bed covers. See, for example, the signal detector systems illustrated in U.S. Pat. No. 4,020,482 to Feldl and U.S. Pat. No. 4,295,133 to Vance. Other systems employ several pneumatic or electrical detectors incorporated into a movable mat or pad. Such systems are shown in U.S. Pat. No. 4,195,287 to McCoy et al; U.S. Pat. No. 4,175,263 to Triplett et al; U.S. Pat. No. 4,228,426 to Roberts; and U.S. Pat. No. 4,242,672 to Gault.
The aforementioned systems rely on manual positioning of the detector strip or mat in the bed. Aside from the effort required to effect installation, such systems suffer from several inherent defects. First, errors in positioning the detector may result in erroneous indications of the presence or absence of the patient in the bed. This is particularly true of signal detector systems which detect the patient's weight in a relatively small area in the bed. Improper handling of electrical tape switch detectors during repositioning may result in damage to the detector. In articulated beds, the adjustment of the bed may cause movement or bunching of the springs, mattress and/or detector which can result in erroneous indications.
It is an object of the present invention to provide a simply and inexpensively constructed bed departure detection apparatus which is permanently installed in the bed.
It is another object of the present invention to provide a multiple detector system in which detectors are installed in fixed, proper locations in the bed springs.
It is another object of the present invention to provide a multiple detector monitoring system for an articulated bed which minimizes erroneous indications caused by movement or bunching of the springs, mattress or detectors when the bed is adjusted.
Bed exit detector systems are shown in U.S. Pat. No. 3,325,799 to Farris and U.S. Pat. No. 3,991,414 to Moran which employ straps or wires stretched from point to point in arrays in the bed. The wires or straps are coupled to strain gauges or switch cartridges. Aside from its clear structural difference from the present invention, the Farris system is apparently not adapted for use in an articulated bed. The Moran system apparently requires that the detector system tension be adjusted when the articulated bed is set in a new position.
It is an object of the present invention to employ a permanently installed detector system for an articulated bed which does not require sensitivity adjustments when the bed is set in a new position.
Bed departure detection systems must quickly and accurately inform responsible health care personnel of patient movement so that falls or other hazards can be avoided. A number of the systems mentioned above employ external circuitry and existing nurse call signalling links to provide an indication of patient departure. Other external circuitry for this purpose is shown in Reissue Pat. No. 28,754 to Cook et al. It is useful for such systems to differentiate a bed exit signal from a patient initiated nurse call, so that higher priority bed departure indications will be recognized as such and distinguished from more routine calls.
It is an object of the present invention to provide an easily and inexpensively constructed interface between a bed detection apparatus and a remote, central call station, which clearly distinguishes a bed departure indication from other nurse calls.
It is another object of the present invention to provide a bedside external circuitry package which may be selectively used with a permanently installed bed departure detector and existing communication links to provide a quick and accurate indication of bed departure to responsible personnel at a remote location.
These and other objects and features of the present invention will become apparent from the claims and from the following description when read in conjunction with the accompanying drawings.